In many medical environments, a medical fluid is injected into a patient during diagnosis or treatment. One example is the injection of contrast media into a patient to improve nuclear medicine, Magnetic Resonance (MR), CT, optical, Angiographic, or Ultrasound imaging, using a powered, automatic injector.
Injectors suitable for these and similar applications typically must use a relatively large volume syringe and be capable of producing relatively large flow rates and injection pressures. For this reason, injectors for such applications are typically motorized, and include a large, high mass injector motor and drive train. For ease of use, the motor and drive train are typically housed in an injection head, which is supported by a floor, wall, or ceiling-mounted arm.
The injection head is typically mounted on the arm in a pivotal manner, so that the head may be tilted upward, with the syringe tip above the remainder of the syringe, to facilitate filling the syringe with fluid, and downward, with the syringe tip below the remainder of the syringe, for injection. Tilting the head in this manner facilitates removal of air from the syringe during filling, and reduces the likelihood that air will be injected into the patient during the injection process. Nevertheless, the potential for accidentally injecting air into a patient remains a serious safety concern, and if overlooked may be fatal in some instances.
In addition to the injection head discussed above, many injectors include a separate console for controlling the injector. The console typically includes programmable circuitry which can be used for automatic, programmed control of the injector, so that the operation of the injector can be made predictable and potentially synchronized with operations of other equipment such as scanners or imaging equipment.
Injector systems may also be configured with two heads. Respective syringes in each head are interconnected with tubing forming a “Y,” or “Y-tubing,” leading to a single intravenous injection site on a patient. For example, such syringes may contain a contrast media and a saline solution, and may be used in combination to prevent clotting.
One particular operational routine performed by the injector system is that of purging any air from the syringe, such as air introduced during filling, and any extension tubing used therewith. This purging sequence for a power injector typically requires that the operator tilt the head upright and advance the plunger so as to force any air from the syringe and extension tubing. This further reduces the likelihood that air will be injected into the subject during the injection process. This manual process is typically performed by trained clinicians to ensure reasonable efforts are taken to minimize or eliminate air from being injected into a patient.
Accordingly, a need exists to simplify the set-up sequence in power injectors so that an operator may automatically purge air from an injector prior to injection of a medical fluid into a patient.
In many applications, it is desirable to use an injector with multiple different size syringes. For example, it may be desirable to use a smaller syringe for pediatric use than for adult use. To facilitate the use of different syringe sizes, injectors have been adapted to include memory containing parameters for multiple different size syringes and to allow an operator to enter parameters or the type of syringe. Other injectors have been adapted to receive various heads specific to different syringes and select parameters for a syringe based thereon.
Irrespective of the particular size or construction of a syringe, each syringe may trap or contain a certain amount of air or gas based on the size or construction of the syringe. For example, one size of pre-filled syringe is produced with a small, e.g., approximately 1 milliliter (ml), nitrogen bubble to facilitate sterilization.
Accordingly, an auto purge for an injector need be adaptable to a variety of injectors. Further, an auto purge for an injector need work with pre-filled and/or empty syringes of varying sizes.